Mitosis, Meiosis, and Cancer – Flashcards
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How many chromosomes are found in a human cell?
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46 chromosomes, 23 pairs (one from mom and the other from dad) in nuclei
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What is the ending result of mitosis?
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*TWO NEW, IDENTICAL CELLS (DIPLOID CELLS) *
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What is a chromosome?
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A piece of DNA that contains part of the cells total genetic information that is made up of DNA and proteins
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What does mitosis do?
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Cell division, reproduction of cells. Without mitosis, humans would not grow and their cells would not multiply --> death. This process is done by human body cells.
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Interphase
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The first stage of the cell cycle. - During interphase, there are 92 chromosomes, but when mitosis takes place, the cell splits into 46 chromosomes - Most of a cell's life is spent during interphase (90%) G1 (Growth or Gap 1) - Cell spends most of its time in this phase - Cell's size increases - Synthesizes new organelles and proteins - Period of intense growth and activity S (Synthesis) - DNA Replication - New DNA is synthesized when the chromosomes are replicated - Ends up with twice as much DNA as before G2 (Growth or Gap 2) - Shortest phase - Most of the organelles and molecules are produced and prepared for cell division - Period of intense growth and activity
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Mitosis
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M (Mitosis) - Not apart of interphase - Cell division (division of the cell's nucleus) - 10% (shortest time cell is in) - PMAT!!!!! Prophase, Metaphase, Anaphase, and Telophase (Cytokinesis) - Cytokinesis: division of the cytoplasm - Produces two daughter cells - This process is very fast
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Why is the nucleus important for cells?
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- Holds DNA (genetic information) - New cell must have the same info for the cell to be identical in mitosis
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Why are chromosomes essential?
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They organize long strands of DNA.
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What has to happen before the splitting of the cell?
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DNA replication
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Prophase (Mitosis)
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- End of prophase: nuclear envelope is gone - Chromosomes are visible and are condensing - Spindle fibers are forming - longest stage of mitosis
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Metaphase (Mitosis)
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- M for Middle - Chromosomes are aligned in the middle
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Anaphase (Mitosis)
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- A for Away or Apart - Spindle fibers attach to the chromosomes - Chromosomes are moving away from each other to the opposite sides of the cell or to the poles
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Telophase (Mitosis)
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- T for Two - New nuclei are forming at each side around the chromosomes to create new, identical daughter cells
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Cytokinesis (Mitosis) Animal Cells
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- Cell movement - Cleavage furrow splits the cell into two - Two new, identical daughter cells are formed - Not apart of mitosis, but can be done throughout the process of mitosis
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Why is mitosis important?
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- Useful for cancer research - Repairs damage (i.e. wounds, cuts) - How humans grow and develop
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Diploid cells
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A cell containing two sets of chromosomes (2n), one set inherited from each parent. Two copies.
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Haploid cells
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Cells (gametes) that have half the amount of chromosomes (n) (23). One copy.
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Gametes
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Sperm and egg cells (sex cells)
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Why does it make sense that an egg cell and sperm cell have 23 chromosomes each?
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Because an egg cell and sperm cell meet creating 46 chromosomes.
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Where is meiosis done?
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This process is done in the ovaries or testes.
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Why is meiosis important?
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*Creates variation*, prevents offspring being clones. It also creates 4 unique gametes by the end of the process.
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What is meiosis all about?
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Sperm and egg cells and reduction division.
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How many chromosomes does meiosis start and end with?
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Starting human cell (46) --> Ending cell, gamete (23)
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What is the difference between mitosis and meiosis?
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Mitosis- diploid, two new, identical daughter cells Meiosis- haploid, four new, very different daughter cells, known as gametes
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Interphase in meiosis.
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Interphase is the same in starting meiosis as it is in starting mitosis. It happens once before the process of meiosis.
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What happens when an egg and a sperm come together?
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When the egg and sperm come together to form a zygote, with 46 chromosomes.
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In meiosis, how many times are the stages repeated.
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TWICE PMAT x2 !!!!!!!!!!!
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Prophase 1
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- chromosomes condense and thicken - align and match with their homologous pairs - crossing over
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Homologous Chromosomes
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Chromosomes that look alike and carry genes for the same traits
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Crossing over
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The transferring of genetic information between two nonidentical chromosomes. Recombination of chromosomes --> VARIATION
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Metaphase 1
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- M for Middle - chromosomes line up independently in the middle and are next to each other XX XX XX
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Anaphase 1
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- A for Away or Apart - Chromosomes move apart from each other by attaching to spindle fibers - Tetrad
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Tetrad
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four chromatids that form during meiosis
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Telophase 1
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- produces two new haploid cells (for now) - soon needs to split again
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Prophase 2
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- NO HOMOLOGOUS PAIRS OR CROSSING OVER (already done) - Spindle fibers are forming
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Metaphase 2
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- M for Middle - chromosomes line up singly in the middle (not in pairs)
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Anaphase 2
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- chromatids are pulled apart to opposite sides of the cell
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Telophase 2
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forms 4 new cells O O oo oo
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What is unique about the four new cells produced in meiosis?
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Cells are going to be different from each other and from the original starting cell. Original = 46, New = 23
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Karyotype
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a picture of organized chromosomes according to size and banding patterns.
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Female
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Egg cells, XX
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Male
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Sperm cells, XY
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What does the end of meiosis 2 look like?
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Sister chromatids split apart and four new, different haploid cells (gametes) are produced.
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Centromere
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Area where the chromatids of a chromosome are attached
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Chromosomes numbers during mitosis
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Chromosomes Before interphase: 46 After interphase: 46 During mitosis*: 46 After mitosis (per daughter cell): 46 Chromatids Before interphase: 46 After interphase: 92 During mitosis*: 92 After mitosis (per daughter cell): 46 * in anaphase, one can argue that there are 92 chromosomes
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Chromosome numbers during meiosis
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Chromosomes Before interphase: 46 After interphase: 46 During meiosis 1: 23 After meiosis 2: 23 Chromatids Before interphase: 46 After interphase: 92 During meiosis 1: 46 After meiosis 2: 23
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What is the difference between asexual reproduction and sexual reproduction?
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Asexual: one organism (its own genetic information) to produce offspring, *only do mitosis* Sexual: two organisms (two genetic information) to produce offspring, *does both mitosis and meiosis*
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What is cancer?
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Cancer is uncontrolled and abnormal cell growth.
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How do cancer cells form?
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- Cells are not regulated correctly, do not pass the checkpoints, and do not self destruct with aptomitosis, so they begin to grow uncontrollably, and cancer begins
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How does cancer continue to grow?
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Cancer has the ability to secrete their own hormones (supply the cancer cells with nutrients meaning it can continue growing- not healthy). Cancer cells continue growing, and do not stop when the body tells it to.
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Why is cancer bad for our bodies?
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Prevents us from keeping homeostasis and cell division is constant and rapid
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What are the risk factors of cancer?
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- Genetics (hereditary) - Life Style (too much sun) → skin cancer
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What does one MUST have to have viable offspring?
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One must have 1 X to have viable offspring
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Cell Cycle
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- Cells usually stop dividing once they come in contact with each other - Cells grow rapidly when injured to repair the body - Cell stop growing once healed - Internal and External regulators
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Cyclins
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Cyclins are proteins that tell the cells to divide and regulate other things in the cell cycle
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Benign
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Non cancerous tumor
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Malignant
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Cancerous tumor
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Metastasis
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Cancer has spread to other parts of the body
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Mutation
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genetic change mutations can be neutral, helpful, or harmful
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How can we treat cancer?
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- Chemotherapy - Radiation - Surgery
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How does interphase and prophase look different?
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In interphase, DNA is linear and all over the place, whereas in prophase, the chromosomes thicken and condensed and are visible. Also, by the end of prophase the nuclear envelope goes away and spindle fibers start to form.
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What is the difference between cancerous and non cancerous cells? What are the similarities?
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Differences - They are Opposites Cancer cells multiply and grow at an abnormal rate Non Cancerous Cells cannot move to other places of the body (Metastasis) and cells are programed to be destroyed (apoptosis) Similarities - They both do mitosis (cell division), They both can have a tumor
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What are the similarities and differences of Prophase 1 in Meiosis and Prophase in Mitosis?
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Similarities - Form spindle fibers and centrioles, chromatin condenses to chromosomes, nuclear membrane breaks down Differences - Prophase 1 - Cross Over and Homologous chromosomes Prophase - Do not cross over, sister chromatids
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Why do gametes have half the number of chromosomes? When a life is created, when does the number become back to 46 chromosomes?
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Gametes are haploid cells which contain 23 chromosomes. We need this because when a sperm and egg cell come together, they form a zygote which is a diploid cell which contains 46 chromosomes.
